Coronal leakage has been recognized as a cause of pulpal and periradicular disease. Although cleaning and shaping of the root canal system is considered paramount, obturation of the system is an important step in endodontic success. The purpose of this study was to evaluate coronal bacterial leakage in teeth obturated with the System B continuous wave of condensation technique, followed by an Obtura II backfill, versus teeth obturated using the lateral condensation technique. Sixty single-rooted bilaterally matched teeth were evaluated in this study. An anaerobic bacterial leakage model was used. Results indicate that microbial coronal leakage occurs more quickly using lateral condensation than with the System B continuous wave of condensation and Obtura II backfill. This difference was statistically significant (p < or = 0.05). However, there was no statistical difference between groups 1 and 2 in the numbers of teeth that demonstrated bacterial leakage at the end of the study.